455 Low RPM

« **on:** August 16, 2019, 09:47:58 am »

Hey folks,

Our '72 Sea Ray has a 455 with a Berkeley 12JC-A and it tops out at only 3,600 rpm.

We purchased the boat from an estate sale so we don't know too much about it. The engine was built in the mid 90's. It runs smooth and sounds good. No missing or pings. The pump is clear of any debris. It has a Quadrajet that is opening fully, compression test is good. MSD 6AL with a 5000 chip in it.

Any thoughts on where my HP went?

Bill

« **Reply #1 on:** August 16, 2019, 01:04:59 pm »

A couple of things-

Secondaries not opening.

Timing way out.

Tach reading wrong.

Starving for fuel.

Good luck,

Dan'l

« **Reply #2 on:** August 16, 2019, 04:19:39 pm »

Yeah check the tach mine is off by about a 1000 rpm its original same as the speedo is of by about 10mph....the olds are not a high rev engine I’m guessing my olds spins about 4400 rpm maybe 4600 and i only get on it for maybe 10 seconds or less

« **Reply #3 on:** August 16, 2019, 07:00:52 pm »

Thanks for the replies guys!

I am planning on new gauges this winter but I'm going to grab a new tach right away. I just got a new set of plugs for it, it had Champions set at .060"!! Seemed a bit big, I'll run the new ones at .035". I will check for correct TDC on balancer and recheck timing too.

I'll update when I can!

Bill

« **Reply #4 on:** August 16, 2019, 07:04:46 pm »

When ya do the plugs check the cap and rotor and points if ya have a old Mallory.

« **Reply #5 on:** June 01, 2020, 09:22:12 pm »

you said the secondaries are opening fully, did you see this while running the engine? I say no way, my 455 would turn 4000 on just the primaries (holley) but even the quadrajets smaller primaries will probably turn 3600 on their own. Please let us know what you found out. im curious

billandlori

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